1. Field
Embodiments of the present invention relate to heat exchangers.
2. Description of Related Art
In diesel fuel powered transportation environments, extremely cold temperatures adversely affect diesel engine operation. Generally, large diesel engines, such as locomotive engines, are not shut down during cold weather conditions due to the difficulty in restarting such engines. Diesel engines do not have the benefit of an electrical spark to generate combustion and must rely on heat generated by compressing air in order to ignite fuel in the engine cylinders.
In low temperature conditions (ambient temperatures below about 40° F., for example), various factors contribute to the difficulty in starting a diesel engine. For instance, cold ambient air drawn into the engine must be increased in temperature sufficiently to cause combustion. Additionally, diesel fuel tends to exhibit poor viscous qualities at low temperatures. Moreover, in extremes of cold, diesel fuel tends to gel, thus making engine operation difficult.
When locomotives are operated in cold climates, high viscosity and wax clouding of the cold diesel fuel tend to clog fuel filters and fuel injection nozzles. Viscosity also may affect injector lubrication. Fuels with low viscosity may not provide sufficient lubrication for the precision fit of fuel injection pumps or injector plungers, resulting in leakage or increased wear. Fuels that do not meet viscosity requirements can lead to performance complaints. Fuel atomization is also affected by fuel viscosity. Diesel fuels with high viscosity tend to form larger droplets on injection, which can cause poor combustion and increased exhaust smoke and emissions.
In recent years, higher boiling point wax fractions have been used in diesel fuels. Such wax fractions tend to more readily crystallize out in engine parts and fuel lines, making engine starting and operating even more difficult.
Existing fuel heaters are complex, unwieldy, and not optimally effective. Accordingly, there is a growing need for an improved fuel heater.